Prince CTS Thunderstick Oversize pricing

I have a Prince CTS Thunderstick Oversize racquet that I want to sell but I don't know how to determine a fair price. It is brand new (in that it was never used and still has the original packaging labels, etc., on it. It is in a case but it doesn't have strings on it. On the inside of an open triangle area is printed "PRINCE <N> PATENTED, (C) 1988 PRINCE MFG, INC. The grip size is 4 3/8, No. 3. I won this racquet from a radio station a long time ago and it's been stored in our closet ever since. When I first won it they told me it was valued at $300, but I'm sure it's not worth that now. Can anyone tell me where I can find current pricing for this? Thanks.
p.s. Sorry this is so wordy, but I didn't want to omit any info that might be important!